The present invention relates to a coupling device designed so that a jewel or any other ornamental piece can be readily replaced in accessory articles or ornamental buttons such as a finger ring, an earring, a brooch and the like.
In various accessories or ornamental buttons as described above, a commonly used coupling means permitting a base piece having a jewel or any other ornamental piece mounted thereon to be easily attached to and easily detached from a receiving member is used which magnetically or threadingly couples the base piece and the receiving member.
With a magnetic coupling in the prior art, attachment and detachment are easy, but there is a fear that the base piece may be relatively easily dropped off upon contact with another object. On the other hand, with a threading coupling, it is often difficult to perform the operation of turning both of the base piece and the receiving member several times in attaching and detaching them. Additionally, the machining work of threading a smaller part can be very troublesome.
The present invention provides a coupling device for an ornamental piece intended to overcome the disadvantages associated with the above prior art and uses both a magnetic coupling and means for preventing drop-off comprising a projection and an engaging groove to facilitate the attachment and detachment and to ensure a reliable and firm coupling.
The coupling device of this invention has a base piece adapted to have the ornamental piece mounted thereon and a receiving member to be coupled with the base piece, the base piece and the receiving member being coupled together by fitting and connecting a coupling portion of the base piece into a recess in the receiving member, wherein:
a step-shaped engaging guide groove is provided on the internal side surface of the recess of the receiving member, the engaging guide groove comprising an upper groove portion which communicates with a periphery of the surface having an opening of the recess and which extends towards the bottom of the receiving member, an intermediate groove portion which bends from the lower end of the upper groove portion and which extends along the circumferential direction, and a lower groove portion which bends from the remaining end of the intermediate groove portion towards the bottom of the receiving member, PA0 a projection provided on part of the external surface of the coupling portion is fitted into said step-shaped engaging guide groove and then turned and further pushed in the direction of coupling to thereby detachably couple the base piece and the receiving member, and PA0 magnet pieces are opposingly provided on the lower surface of the coupling portion and on the bottom surface of the recess.
Further, in the coupling device of this invention the shapes of the opening of the recess and of the bottom surface of the recess in the receiving member are formed identically, with the projected shape of the base piece having the projection on part of the external surface thereof.
Further, in the coupling device of this invention the shape of the bottom surface of the recess is formed identically with the projected shape of the base piece having the projection on part of the external surface thereof.